<template>
  <div class="contain">
    <div class="code">
      <canvas @click=draw(show_num)  id="canvas" width="500" height="40"></canvas>
    </div>
  </div>
</template>

<script>
export default {
  name: "ConfirmCode",
  data(){
    return{
      show_num:[]
    }
  },
  methods:{
    randomColor(){
      var r = Math.floor(Math.random() * 256);
      var g = Math.floor(Math.random() * 256);
      var b = Math.floor(Math.random() * 256);
      return "rgb(" + r + "," + g + "," + b + ")";
    },
    draw(show_num){
      var canvas_width=100;
      var canvas_height=40;
      var canvas = document.getElementById("canvas");//获取到canvas的对象
      var context = canvas.getContext("2d");//获取到canvas画图的环境
      canvas.width = canvas_width;
      canvas.height = canvas_height;
      var sCode = "a,b,c,d,e,f,g,h,i,j,k,m,n,p,q,r,s,t,u,v,w,x,y,z,A,B,C,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,W,X,Y,Z,1,2,3,4,5,6,7,8,9,0";
      var aCode = sCode.split(",");  //把字符串分割成字符串数组。
      var aLength = aCode.length;//获取到数组的长度
      for (var i = 0; i < 4; i++) { //这里的for循环可以控制验证码位数（如果想显示6位数，4改成6即可）
        var j = Math.floor(Math.random() * aLength);//获取到随机的索引值,random() 方法可返回介于 0（包含） ~ 1（不包含） 之间的一个随机数。
        // var deg = Math.random() * 30 * Math.PI / 180;//产生0~30之间的随机弧度
        var deg = Math.random() - 0.5; //产生一个随机弧度
        var txt = aCode[j];//得到随机的一个内容

        show_num[i] = txt.toLowerCase();
        var x = 10 + i * 20;//文字在canvas上的x坐标
        var y = 20 + Math.random() * 8;//文字在canvas上的y坐标
        context.font = "bold 23px 微软雅黑";
        context.translate(x, y);
        context.rotate(deg);
        context.fillStyle = this.randomColor();
        context.fillText(txt, 0, 0);
        context.rotate(-deg);
        context.translate(-x, -y);
      }
      sessionStorage.setItem("code",show_num.join(""))
      for (var i = 0; i <= 5; i++) { //验证码上显示线条
        context.strokeStyle = this.randomColor();
        context.beginPath();
        context.moveTo(Math.random() * canvas_width, Math.random() * canvas_height);
        context.lineTo(Math.random() * canvas_width, Math.random() * canvas_height);
        context.stroke();
      }
      for (var i = 0; i <= 30; i++) { //验证码上显示小点
        context.strokeStyle = this.randomColor();
        context.beginPath();
        var x = Math.random() * canvas_width;
        var y = Math.random() * canvas_height;
        context.moveTo(x, y);
        context.lineTo(x + 1, y + 1);
        context.stroke();
      }
    }

  },
  mounted() {
    var show_num = [];
    this.draw(show_num)
  }
}
</script>

<style scoped>
.contain{
  width:300px;
  height:60px;
  margin:0px auto;
}
#canvas {
  vertical-align: middle;
  box-sizing: border-box;
  border: 1px solid #ddd;
  cursor: pointer;
}
</style>
